Lawn trimmer



Jan. 16, 1951 s. H. BOGGS 2,538,230 I LAWN TRIMMER Filed Dec. 29, 1947 2 Sheets-Sheet l IIII /0 22 a 0 o 24 M 7 /6 Z3 m r l/ II" 5AM H. B0668 INVENTOR.

ATTORNEY Jan. 16, 195 1 s. H. BOGGS 2,533,230

LAWN TRIMMER Filed Dec. 29, 1947 2 Sheets-Sheet 2 5A H. B0665 INVEN TOR.

ATTORNEY Patented Jan. 16, 1951 UNITED STATES PATENT OFFICE LAWN TRIMMER Sam H. Boggs, Dallas, Tex.

Application December 29, 1947, Serial No. 794,266

5 Claims. 1

This invention relates to new and useful improvements in lawn trimmers for trimming the vegetation, such as grass, along walks, drives, curbs and the like; and more particularly to a power driven rotary trimmer.

One object of theinvention is to provide an improved power driven rotary lawn trimmer of the character described, having improved and novel cutting means; wherein said cutting means includes a plurality of flexible wires carried by a rotating hub and driven at a high angular velocity to whip or cut off grass along the edges of walks, driveways, curbs and the like.

An important object of the invention is to provide an improved lawn trimmer, of the character described, wherein the flexible cutting wires are loosely mounted on the hub so as to be freely swingable thereon to reduce breakage and to accommodate misalignment of the cutting device with the edge of the Walk or drive or curb along which the grass is being trimmed.

Another object of the invention is to provide in-a lawn trimmer of the character described an improved simple mounting for the flexible cutting wires, whereby such cutter wires may readily be installed or replaced when worn or broken.

A further object of the invention is to provide a lawn trimmer of the character described wherein the cutting head of the trimmer is reversible in position on the carrier, whereby the trimmer may be used for trimming along the edges of walks, curbs, drives and the like in opposite directions.

Still another object of the invention is to provide in a lawn trimmer of the character described means for adjusting the height of the cutting head, whereby the position of the cutter wires with respect to the lawn being" trimmed may be controlled and adjusted, to assure proper trimming of grass.

A still further object of the invention is to provide in a lawn trimmer of the character described a protective shield for the high speed rotating cutter wires for preventing injury to the user of the trimmer, said shield also being reof smaller caster wheels I3 Figure lis a side view, in elevation, of a lawn trimmer constructed in accordance with the invention, I

Figure 2 is a plan view of the same,

Figure 3 is a view, partly in elevation and partly in section, of the cutter head, and

Figure 4 is a View, partlyin elevation and partly in section, of the cutter wire carrier hub.

The numeral Ifl designates a base plate or frame, which is preferably substantially diamond-shaped. A pair of ground wheels II are mounted on an axle l2 which is secured in any desirable manner to the underside of the frame member substantially centrally thereof. The ground wheels preferably are rubber tired to facilitate movement of the device. One of a pair is eccentrically mounted in ,a frame M at each end of the base plate H), the carrier l4 being secured in each case near the outer end of a swingable half [5 of a hinge member I6 having its other half secured to the base member [0. The caster wheels l3 are so positioned and arranged that when one of the caster wheels is in contact with the ground the other wheel is spaced from the ground, whereby the base plate H1 is tiltable about the axis of the ground wheel axle [2. Wing nuts I! are threaded onto bolt [8 which extend upwardly through slots l9in' the movable hinge sections [5, for holding the movable hinge section in the position shown in Figures 1 and 2. When the wing nuts I! are removed, the swingable hinge sections I5 may be lifted to completely swing the caster wheels upwardly and out of supporting position.

A power unit or motor 20 is mounted on the upper surface of the base plate is substantially centrally thereof and with its drive shaft projecting parallel to the axle I2 on which the ground wheels are mounted, whereby the drive shaft extends transversely of the longitudinal axis of the base plate. The power unit may be an electric motor, a small internal combustion engine or any other suitable desired source of power, but is shown as being an electric motor. An elongate tubular handle 2i has a l J- shaped yoke 22 releasably secured at its inner end, and the yoke is swingably mounted by bolts 23 to the upper portion of the frame or housing of the motor 20. An electrical conductor cord 24 from the motor extends longitudinally through the handle to a point near its outer end, where it is connected to aswitch 25 for controlling the fiowof electricity from a source of power to the motor. The cord then extends outwardly through a lateral opening near the outer end of the handle. A grip piece 26 is fixed on the extreme outer: end of the handle, whereby the user may manually maneuver the device.

An elongate rectangular side plate 30 is preferably formed integral with the base plate Hi, being connected thereto by a throat piece or neck 3!, and said side piece extends parallel to the longitudinal axis of the base member. An upright post member 32, having a large rectangular base 33, is supported upon the upper surface of the side piece 3% and an elongate supporting arm 3 is pivotally connected at one end to the upper end of the post 32 by means of a bolt 35. The outer portion of the arm 34 is tubular and receives a shaft 36 which is slidable therein and is held in adjusted positions longitudinally of the arm by means of a set screw 31. A cutter head 36 is carried on the outer end of the shaft 36, as is clearly shown in Figure 2.

A pair of upstanding supporting screws 40 are threaded into bosses 4! formed in the base 33 on each side of the upright post. Each supporting screw is provided with a central radial flange 42 formed integral with the screw and adapted to be engaged by and to support the elongate supporting arm 34, as clearly shown in Figures 1 and 2. The supporting screws are movably held in various adjusted positions by coil springs 53 interposed between the flanges 42 and the bosses 4!, whereby each of said screws is prevented from readily moving from any desired adjusted position by the frictional engagement of the spring with said flange and the boss.

As best shown in Figure 3, the cutter head 38 includes an elongate substantially cylindrical housing 45 having bearings 46 at each end releasably retained in the housing by a retaining bushing 4? at the inner end of the housing and a similar retaining bushing 43 at the outer end of the housing. The bearings rotatably. support a cutter shaft t9 which extends axially through the housing. A driven pulley 50 is mounted on the inner end of the shaft 49 and is connected by means of a belt 5! to a large driving pulley 52 which is mounted on the drive shaft of the motor of power unit 20, wherebyv the motor drives the cutter shaft.

A cutter hub 55 is removably mounted. on the Q outer end of the cutter shaft 49, being secured thereon by a set screw 5%. The cutter hub is provided with a plurality of radially extending cutter carrier arms 51, which are shown in the drawings as being four in number but may be provided in any desired number. Cutter wire receiving openings 58 are formed at the outer end of each carrier arm 5? for receiving and supporting cutter wires 59. The cutter wires are preferably formed of resilient or spring wire, for reasons which will be hereinafter more fully explained. Wire inserting slots 68 extend radially inwardly of each carrier arm from the openings 58 and are then turned at substan tially right angles to extend to one edge of the carrier arm, as is shown in Figure 4, to provide substantially L-shaped wire inserting slots by means of which the eye loops 59a of the cutter wires 59 may be slipped into the openings 58 at the outer end of the carrier arms 57. A retaining washer 6! is supported against the outer surface of the hub 55 and is of such a diameter that it extends substantially to the openings 58 in the supporting arms 57, whereby the inserting slots 60 are covered by said washer to prevent the cutter wires 59 from slipping out of the openings 53 through said insertin slots. The washer is held in place by a bolt 62 which is threaded into the outer end of the cutter shaft 39 and presses the washer against the hub.

The openings 53 through the carrier arms 51 are preferably flared on each side, as best shown in Figure 3, to accommodate the curvature of the eye loops 59a of the cutter wires. The end of the wire at each of the eye loops of the cutter wires is welded to the main portion of the wire to completely and positively close the eye, to prevent the eye loops from spreading open when the cutter wires are revolved at high speed.

An arcuate shield member 65, having a handle 65 mounted thereon, is supported on an arm 6? which has a cylindrical sleeve 68 at its lower end. The sleeve is slidably mounted on the outer end of the tubular housing 45 of the cutter head, being retained in position thereon between an external annular collar 69 formed on the housing and an external annular flange 10 formed on the retaining bushing 48 at the outer end of the housing. A. ball catch member H is mounted in an openin i2 formed in the sleeve 68 and is adapted to engage in a recess 73 formed in the outer surface of the housing 45 to retain the arm 6'; in position for supporting the shield 55 in the shielding position shown in Figures 1 and 2. The ball is pressed inwardly against the housing 45 by a leaf spring i4 secured at one end to the sleeve 68 and engaging over the ball.

If desired, the cutter head may be swung from the position shown in Figure 2 to a position near the opposite end of the frame member II] by swinging the supporting arm 3'3 about the bolt 35 at the upper end of the upright post 32 until the supporting arm engages the flange 42 on the supporting screw 19 on the opposite side of said post. Thus, the cutting device may be reversed in direction, or may be used to out the opposite edge of a walk without being moved off the walk. A depression similar to the depression 13 is formed in the housing at a point spaced from the depression 13 so that the looking ball i! may engage in said depression to reposition the shield 55 in proper shielding position when the cutter arm is swung in the manner just described.

In use, when the motor or power unit 20 is in operation, the pulley 52 drives the belt 5| to turn the pulley 50 and rotate the shaft 49 on which said pulley is mounted. As the shaft 49 is rotated, the cutter hub 55 is likewise rotated and the carrier arms 51 are swung about the shaft. The cutter wires 59 carried at the outer end of each of the carrier arms 5'! are thus swung rapidly about the shaft 49 and the centrifugal force created by such rotation maintains the cutter wires in substantially the planar position shown in Figures 1 and 3. The high speed at which the cutter wires are swung will cause the wires to whip or cut off grass or other vegetation with which they come into contact.

The weight of the cutter head will normally tend to tilt the frame member or base plate Ill downwardly in the manner illustrated in Figure 1, whereby the caster wheel i3 on the end of the frame member nearest which the cutter head is supported will be moved into contact with the ground, sidewalk, or the like to prevent further tilting of the frame member. The height of the cutter head above the ground may be adjusted by adjusting the position ofthe flanges 42 on the supporting screws 40 to raise and lower the Warm 34 until the outer ends of the cutter wires 59 are positioned in proper cutting relationship withthe vegetation to be cut. The tip ends of the cutter wires, which travel at high speed, may thus be set to whip or cut off such vegetation.

Since the cutter head is so positioned that the cutter wires are revolved in a plane spaced laterally beyond the ground wheel 1 I, it will be seen that the ground wheels may remain on the walk, drive or the like and "that the cutter wires may be moved along the edge of such walk or drive to trim the grass or other vegetation along the edge thereof.

It is not necessary that the flexible resilient cutter wires be provided with sharpened cutting edges. The high speed at which the tips of thewires travel causes such tip ends to slice or "w hip-ofi the vegetation with which they come in contact, so that the wires may be, and preferably are, smooth round material without sharpened edges,

Due to the resiliency of the cutter wires 59,

and their loose mounting in the cutter hub 55, it

cutter wires be loosely mounted on the cutter hub, qwhereby they may readily swing in the openings 58 in the radial carrier arms 51 of the hub. Thus,

the cutter wires are not required to flex but may swing freely and easily in the opening, and any tendencyto break the cutter wires is substantially reduced or eliminated. v

Manifestly should one of the cutter wires break, or should all the cutter wires become sufliciently worn torequire replacement, it is only necessary to unscrew the b'oltpfiz from the "end of the cuttjer shaft 49 and remove the washer 6| which covers the inserting slots 60. The eye loops 59a of the cutter wires may then be slipped outwardly from the openings 58 along such slots to disengage the cutter wires from the cutter carrier arms. New wires may then be reinserted through the inserting slots 60 into place in the openings 58 and the disc or washer 6! replacedand secured in position by means of the bolt 62, whereupon the cutting device is again ready for use.

From the foregoing, it will be seen that an improved power driven rotary lawn trimmer has been provided having novel cutting means, said cutting means including a plurality of flexible wires swingably carried by a rotatin hub and driven at high angular velocity to whip or cut off grass along the edges of walks, driveways, curbs and the like. It will further be seen that the loop mounting of the flexible cutting wires permits the Wires to swing freely on the hub to reduce breakage or damage to said wires and to accommodate misalignment of the cutting device with the edge of the walk, or drive or curb, along which the device is being used to trim the vegetation. Furthermore, it will be seen that an improved simple mounting for the flexible cutting wires has been provided whereby such cutter wires may be readily installed or replaced when worn or broken.

Also, an improved lawn trimmer of the character described has been provided wherein the cutting head of the trimmer is reversible in position on the carrier or frame so that the trimmer may be used for trimming in opposite directions along the edges of walks, curbs and the like. It will also be noted that means has been provided for adjusting the height of the cutting head so that the ends of the cutter wires may be correctly positioned with respect to the vegetation ibeing trimmed, to assure proper operation. Furthermore, adjustable shield has been provided for guarding the user against injuries by the high speed rotating cutter wires, said shield being arranged so that it is adjustable in position and functions to protect the user in either position.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the ap-" pended claims, without departing from the spiritof the invention.

What I claimand desire to secure by Letters patent is:

1. A lawn trimmer including, a frame having ground wheels, a power unit carried by said frame, an elongate supporting arm having one end pivotally carried :by said frame, a housing-' at the outer free end of said arm, a shaft rotat able in the housing, a driving connection between ible resilient wire cutter members each having an eye loop at one end, said cutter membersea'ch having its eye loop extending through the opening in one of the carrier arms whereby each cutter member is freely swingably connected with a carrier arm so as to be freely swingable in the plane of the radially extending carrier arms and angularly with respect to said plane, said loop being of a sufficient size to permit the loop to pass along the slot from the carrier arm opening so that the cutter member maybe disconnected from said carrier arm, and a retaining washer carried by the shaft and engaging the hub to cover the slot in each of the carrier arms for preventing;

displacement of the cutter members-from theQ openings in said carrier arms.

2. A lawn trimmer of the character setfonth in claim 1 wherein, the power unitlist provided with a drive shaft and a flexible tion is provided between the shaftpfi' unit and the shaft in the housing'carrymgt hub, the pivot upon which the supportingar mounted being in axial alignment withth' shaft of the power unit whereby the arm is s wingab through an arc of approximately degreescirr plane vertical to the ground to permit movement ground wheels so that the frame may be tilted to move the cutter members into and out of cutting position, and ground engaging means is carried by the frame spaced from the ground Wheels to limit movement of the frame which moves the cutter members into cutting position, whereby the cutter members are properly positioned in cutting relationship with the ground.

4. A lawn trimmer including, an elongate frame, and axle mounted transversely of the longitudinal axis of the frame at substantially the center thereof, ground wheels on the axle beyond the edges of the frame, a smaller caster wheel mounted at each end of the frame, said caster wheels being so mounted that neither engages the ground when the frame is supported on the ground wheels in a horizontal position whereby the frame must be tilted to cause one of the caster wheels to engage in the ground, said frame being tiltable about the axle of the central ground Wheels in either direction, a power unit mounted substantially centrally of the frame, an elongate supporting arm having one end pivotally supported by the frame, a cutter head carried by the other end of the supporting arm and including a rotatable shaft and flexible resilient cutter members loosely mounted on said 25 shaft, a driving connection between the power unit and the shaft of the cutter head, and stop means on the frame arranged to be engaged by the supporting arm to adjustably support the cutter head in various cutting positions, said supporting arm being swingable through an arc of substantially 180 degrees about the pivot on the frame to move the cutter head from a position near one end of the frame to a position near the opposite end of said frame, the frame being tiltable about the axle of the central ground wheels to move the cutter members of the cutter head into and out of cutting positions at each end of the frame, such tilting movement being limited by the small caster wheels at each end of the frame.

5. A lawn trimmer of the character set forth in claim 4 wherein, a shield member is adjustably mounted on the cutter head for shielding the user of the trimmer against contact with the swinging cutter members, said shield member being shiftable when the supporting arm is swung to move the cutter head to opposite ends of the frame, and means is provided for releasably restraining said shield positioned in protective shielding position at either position of the cutter head.

SAM H. BOGGS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 515,031 Turner Feb. 20, 1894 1,552,750 Lain Sept. 8, 1925 1,870,932 Sternemann Aug. 9, 1932 2,084,398 Jongeneel June 22, 1937 2,209,309 George July 30, 1940 2,341,486 Swertfeger Feb. 8, 1944 2,354,112 Garst July 18, 1944 2,478,813 Esleck Aug. 9, 1949 FOREIGN PATENTS Number Country Date 507,243 Germany Sept. 13, 1930 

